IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry


This article describes the functionality of the RunOnceEx registry key.

More Information

RunOnceEx has the following features:

  • Status - A dialog box is displayed while the items contained in the registry key are being processed. The entries to be processed are grouped into sections and the dialog box highlights the current section being processed. You can disable the status dialog box feature.

  • Performance - The majority of the commands contained in the Run and RunOnce registry keys create separate processes, which is inefficient. The RunOnceEx registry key does not create a separate processes. The RunOnceEx registry key also support a dependency list of DLLs that remain loaded while either all the sections or some of the sections are being processed.

  • Error Handling - If an exception occurs while calling a function in a DLL, the exception is caught and an error dialog box is displayed to the user. You can suppress this error dialog box by using a flag in the RunOnceEx registry key. You can also set a flag to enable log errors and execution of the RunOnceEx registry key.

  • Deterministic - The RunOnceEx registry key sort the entries and sections alphabetically to force a deterministic order.

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